


Poseidon Twins: Mix-Up

by writer171105



Category: Batman - All Media Types, Nightwing (Comics), Percy Jackson and the Olympians & Related Fandoms - All Media Types, Percy Jackson and the Olympians - Rick Riordan, Young Justice - All Media Types
Genre: Dick Grayson Has Secrets, Dick Grayson is Nightwing, F/M, Gen, Metahuman Dick Grayson
Language: English
Status: In-Progress
Published: 2021-01-25
Updated: 2021-01-25
Packaged: 2021-03-17 17:36:04
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 2,756
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28978269
Author URL: https://archiveofourown.org/users/writer171105/pseuds/writer171105
Summary: There are two little known facts about Richard Grayson:He has a twin brotherHis father wasn't really John GraysonORRichard Grayson is Percy Jackson's older twin brother, and the two of them swap places for a week.Plot from @CloeTheTealSnake, who has given me permission to write this.*I own nothing. All images used are not mine.*
Relationships: Annabeth Chase & Dick Grayson, Annabeth Chase/Percy Jackson, Barbara Gordon/Dick Grayson, Dick Grayson & Percy Jackson
Comments: 16
Kudos: 70





	1. Chapter 1

**Author's Note:**

  * For [CloeTheTealSnake](https://archiveofourown.org/users/CloeTheTealSnake/gifts).



> Important Information:
> 
> Warning: This does contain a few spoilers to my story up ahead, but it will make more sense if you do read this first.
> 
> \- Mary Grayson was the twins' biological mother.  
> \- Percy was adopted by Sally Jackson after the Graysons' deaths, just as Dick was taken in by Bruce Wayne.  
> \- Percy was 16 during 'The Lightning Thief'  
> \- Both Dick and Percy are now aware of their demigod status, but Dick's powers are currently being repressed for his protection.  
> \- Neither Bruce nor any of Dick's adoptive family are aware that he is a demigod, although they do know that has a twin whom he hasn't seen for a long while.

**Prologue:**

Richard 'Dick' Grayson-Wayne had secrets. For example, he masquered as a hero with Batman at night, known as Robin.

Or, at least he used to. He had, at the age of 17, recently removed himself from his mentor's shadow, becoming his own hero, known as Nightwing.

Dick also had a, slightly younger, identical twin brother, who went by the name Perseus 'Percy' Jackson. The pair hadn't seen each other for over a year.

The thing was, although they were commonly known as 'The Grayson Twins', their father wasn't _really_ John Grayson at all. Their biological father was, in fact, the Greek God Poseidon, making the pair of them demigods.

That was one of the reasons they hadn't seen each other for such a long time. While Dick's powers were currently repressed for his protection, Percy went to a summer camp known as Camp Half - Blood, where he and other demigods trained to combat monsters and to use the powers they had inherited.

Everything changed though, one Summer when Percy decided to visit his older twin in Bludhaven.

Chaos ensued.


	2. Part 1

**Notes for the Chapter:**

> Here’s to me writing this while listening to “Something Just Like This”.
> 
> Hope you enjoy! 🥰

Percy needed a break. While he loved being at Camp Half-Blood, and he liked  _ most _ of the people there, he needed a break from it.

He sat alone in his cabin, knowing that there should be two occupants, not just himself. He sighed, wondering what he should do, and how to get out. He grinned to himself. Now  _ that _ was an idea.

**…::-::...**

Dick had just arrived back in his Bludhaven apartment after patrol and collapsed onto his bed. It seemed that he had only just closed his eyes when there was a thud in the sitting room. Jolting upright and arming himself with his escrima sticks, he crept silently towards the sound.

In the shadows, he could make a shape moving about. He smirked. If it was a thief, he might as well give them a surprise.

Utilising the training Bruce had given him, he silently stalked the intruder, sneaking up on them. Just as he was about to give them the jump, there was a popping sound above his head, and he looked up to see a cascade of water tumbling down on him. Unfortunately, his reflexes weren't fast enough.

"Percy!" he growled, now knowing exactly who the culprit was. There was a cackle as the lights turned on, revealing Dick's twin doubled over, laughing at his own drenched form. Dick glared at him.

Once Percy had finally calmed down, he grinned at Dick, "Sorry, I couldn't help myself."

"Yeah, right," Dick replied, heading to the bathroom to retrieve a towel. Percy followed behind him, grin still in place.

“I’ll get you back for that one day, you know.”

“Yeah, yeah, I know,” Percy replied, waving his hand dismissively, “I’ll be waiting for it.”

Dick threw the wet towel at him. Percy caught it and laughed, before throwing it back at him. This resulted in a full on scuffle between the two brothers in Dick’s bathroom, in the middle of the night.

By the end of it, they both collapsed onto their backs, breathing heavily and grinning. They caught each other’s eye, and burst into fits of laughter at their own idiocy.

They finally stopped and stood up, Dick pulling Percy into a hug.

“It’s good to see you.”

“I missed you too.”

They stood like that for a moment longer, before breaking apart.

“You know,” Dick said, smirking, “when I finally come to that stupid camp of yours, we could spend more time together.”

“It’s  _ not _ stupid,” Percy defended, indignantly.

“It is, a bit.”

“It’s not.”

“Have you met Diana?”

“Wonder Woman? What does  _ she _ have to do with this?”

Dick grinned, “She went there. And, unlike you, she told me about it.”

Percy smacked his arm, “Cheat.”

**…::-::...**

The pair of them ended up falling asleep side-by- side on Dick’s bed.

Percy was the first to wake, stretching and yawning loudly, disturbing Dick.

“Morning,” he mumbled.

Dick grumbled his reply. Percy scoffed before getting up and heading to the kitchen, planning to make some breakfast.

He didn’t get there. Instead, there was a monster blocking his path. He groaned inwardly as he drew Riptide from his pocket.

“Oh come _on_! I thought we were over this already!”

The monster roared loudly, and Percy could hear Dick fumbling out of bed in alarm.

“Percy!” he called, joining him, “How do we defeat this thing?!”

“Remember the escrima sticks I got you for your birthday?”

“Yeah?”

“Get them and press down hard in the middle.”

Percy tried to fend the beast off as Dick retrieved his weapons. The problem was that the monster didn’t seem all that interested in him. It kept trying to get past him, towards Dick’s bedroom. Percy’s stomach dropped as he realised exactly why.

It was then that Dick appeared, escrima sticks with golden blades at each end brandished threateningly.

“Hey! Big, fat and ugly!” He called, causing the monster to divert it’s attention.

Dick smirked in a way that made Percy’s own blood run cold.

“Come get me.”

The monster ran at Dick with a roar, and Dick leapt out of it’s way, trying to get a swipe at it from behind. The thing turned towards him, slashing with its claws. 

Percy stood absolutely mesmerised as he watched the pair, Dick trying to get a hit with his bladed escrima sticks and the monster lashing back at him with clawed hands. He didn’t even try to assist.

He was finally broken out of his trance when Dick managed to slice through the beast and it disappeared in a flurry of gold dust.

Dick dropped his sticks, breathing heavily from exhaustion as he held his side.

“Thanks for the help, Perce.”

With that, he collapsed to the floor.

Percy rushed to him, removing Dick’s hand to reveal a deep gash in his side.

He fretted. He wasn’t sure what to do. Dick didn’t have his powers, so the water wouldn’t heal him and he didn’t know a _thing_ about normal first aid. Dick was also bleeding heavily, and would most likely bleed out before they got to a hospital.

It was then that the room was bathed in an eerie green light. Percy looked up to see his father’s symbol floating above Dick’s head. Thanking him profusely, he dragged his brother’s unconscious form to the bathroom, dumped him into the bath, and turned on the taps.

The water flowed over Dick, soaking into and healing his wounds. Percy breathed a sigh of relief as he turned off the taps. Dick began to groan as he regained consciousness, before blinking his eyes open, taking in his surroundings.

“Percy, why am I in the bath?”

Percy grinned, “That’s a long story.”

**Notes for the Chapter:**

> I wasn’t exactly sure how to go about this. I had a few ideas and combined them to create my result. I hope it came out alright. Have a great day!


	3. Part 2

**Notes for the Chapter:**

> Yes, there’s more 😉
> 
> I hope I did okay with this. More will be coming soon! I hope you enjoy 😊

After explaining to Dick exactly what had happened while he had been unconscious, Dick leaned back into the sofa and let out a low whistle.

“Wow.”

“Mm hm,” Percy agreed.

There was silence for a moment.

“At least I can go to camp with you now.”

Percy smirked.

It was quiet again.

“Percy?” Dick said slowly, in a way that made Percy suspicious, “I’ve just had an idea.”

“Yes?”

Dick smirked, “How do you feel about messing with the campers for a week?”

Percy grinned, “I’m listening.”

**…::-::...**

The Twins spent the rest of the day organising and making plans.

Dick taught Percy his own unique fighting style while Percy taught him to combat monsters. They exchange their own mannerisms and odd quirks. Lastly, they exchanged clothes and other important information before they were all set.

They grinned mischievously at each other. This week was going to be a blast.

**…::-::...**

Back at the camp, Annabeth was pacing up and down in anxiety. Percy hadn’t been seen since the previous afternoon, and she was getting worried. At first she had thought he’d locked himself in his cabin for a bit of alone time, so she’d left him alone for awhile. It was when he didn’t appear for lunch that she went to check up on him. She hammered on his door and shouted his name, but to no reply. Getting fed up, she slammed the door open and opened her mouth to give him a ticking off, but to her surprise found the place empty. Beginning to worry, she looked around for any sign of where he had gone. She found a note addressed to her, and she opened it.

_ Dear Wise Girl ;-) _

_ If you’re reading this it’s because I’ve disappeared. Don’t worry, nothing’s happened to me, I just needed some time away and decided to visit someone important to me that I haven’t seen for awhile. If I’m not back in the next two days, then you can send out a search party. _

_ Lots of love _

_ Forever your _

_ Seaweed Brain :-p _

Annabeth scoffed and shook her head at her boyfriend’s antics. Sighing, she slipped the note into her pocket and left the cabin, trying to shelve away her worry for after the two days were up.

Which is how she ended up, one and a half days later, anxiously pacing before Percy’s cabin.

“Hey, Wise Girl.”

She turned sharply at the familiar voice.

“Percy!” She shouted, running at him while drawing her dagger from her belt and pointing it at his chest.

“Where have you been?!” She screamed at him, “You can’t just up and disappear like that! You worried me sick!”

“I’m sorry, Annabeth,” Percy said, “I didn't mean to worry you. I just went to visit someone.”

Annabeth was slightly taken aback. It wasn’t like Percy to apologize, he was more likely to shout back at her. She shook her head. Maybe whoever he had seen had knocked some manners into him.

“It’s alright,” she sighed, removing her dagger, “Come, let’s get some lunch while you tell me what you’ve been doing.”

As they walked off, ‘Percy’ smirked. Maybe impersonating his brother might be easier than he thought.

**…::-::...**

Meanwhile ‘Dick’ or rather, Nightwing, currently, had just entered Mount Justice for a mission briefing.

Batman stood before the holo- screen with the rest of the Team, about to explain their mission.

“You will be assisting some of the League with disaster relief in San Francisco. There’s been an earthquake and you are needed to help evacuate civilians from the area.”

Once the Team had acknowledged the information, the group of them headed to the zeta-beams.

Rematerializing in the disaster area, the group of them immediately joined the other Leaguers in clearing rubble and other debris, helping to rescue people from dangerous buildings.

After hours of hard work, all of the heroes regrouped to discuss what had happened.

‘Nightwing’ noticed Wonder Woman glancing at him occasionally, but thought nothing of it. That is, until she pulled him aside to ‘talk’ to him.

“You know,” she began, a smirk pulling at her lips, “It’s been a while since I’ve seen you,  _ Percy _ .”

Percy gulped. Maybe impersonating his brother might not be as easy as he thought.

  
  
  
  


**Notes for the Chapter:**

> Please let me know what you think in the comments!
> 
> Thank you to all of those who have left comments and kudos already. I really appreciate it! 🥰


	4. Part 3

'Percy' sat beside Annabeth at lunch, luckily remembering to offer some of his meal to the fire.

He and Annabeth talked for a while, she asking who he had seen and 'Percy' replying with it being a cousin on his mother's side, _naturally_. 'Percy' found most of the conversation quite Alward, probably due to the fact that it was his brother's girlfriend, his brother whom he was currently impersonating. He hadn't thought of that when planning the whole operation.

He smirked, wondering how the real Percy was getting on, and if he had met Babs yet. Just wait till  _ she _ found out.

**…::-::...**

Meanwhile, ‘Nightwing’ was having an internal debate as to whether or not he would deny or admit to Diana’s accusation. He decided on the latter, as there was always the Lasso of Truth.

“How did you know it was me?”

Wonder Woman smirked, “I am quite close to both you _and_ your brother. I know both of your habits and speech patterns.”

“But, _how_ do you know that he’s my brother? Not even Bruce or Annabeth know!”

“Oh, _please_! I’ve met both of you on separate occasions and seen Dick without his mask before. I would have to be _blind_ not to see the likeness. Besides, I know a Demigod when I see one.”

She studied him for a moment.

“Although, I have to say that I didn’t know both of you, I wouldn’t be able to tell the difference.”

‘Nightwing’ smirked, “So you won’t tell anyone then?”

Diana sighed, “No, I won’t, as long as you reveal yourselves at the end of it.”

As they rejoined the group, he breathed a sigh of relief. He wondered how Dick was holding up, and if he had managed to dupe Annabeth. He smirked. Just wait till  _ she _ found out.

**…::-::...**

It was two days later, at the Camp, where Annabeth was ‘studying’ Percy. He had been acting strangely ever since he came back from his brief disappearance and she wanted to find out why.

She watched him from the shadows of the trees that surrounded the sparring area as he fought against another camper, Riptide gleaming gold in the sunlight. Then it struck her in the way he moved. This  _ wasn’t _ the real Percy.

Removing herself from the shadows, she strolled over as if she’d only just arrived.

“Percy?”

“Yes?” The imposter answered, signaling to his partner to stop the spar.

“Can I talk to you for a minute? In private?”

“Sure,” he replied, recapping Riptide as he joined her, “What about?”

“Let’s go to your cabin,” she replied, “Where no one can overhear us.”

Once they were inside and ‘Percy’ had shut the door, she lunged.

at him, withdrawing her dagger and aiming it at his throat.

“Annabeth!” He exclaimed in shock, “What are you…?!”

“Who are you and what have you done with Percy?” she demanded

“I…”

“Come on, out with it! Who are you working for?”

“I- I’m his brother.”

Annabeth relented slightly in surprise.

“Percy never said that he had a brother.”

“It’s supposed to be a secret,” he admitted, “We were separated when our parents were killed, and my powers were repressed until recently. We hadn’t seen each other for over a year until he snuck into my apartment 4 nights ago.”

“So it was  _ you _ he went to visit.”

“Mm hm.”

“But, you look _just_ like him?”

He grinned, “We’re twins.”

A look of understanding flickered across Annabeth’s face. Demigod twins _and_ sons of one of the Big 3! No  _ wonder _ it had been kept secret!

“And your name is?”

“Richard,” he replied, “but you can call me Dick.”

Annabeth snorted.

**…::-::...**

At the same time, the real Percy was about to meet Babs, Dick’s girlfriend. He knew it was going to be difficult to trick her, as she and Dick had been friends since they were 8 years old. He just didn’t realise it would be  _ impossible _ . Good thing they met at Dick’s apartment 

He had only just opened the, insanely-secure, front door and the next thing he knew he was against the wall, a sharp Batarang pointed at his throat with a furious redhead giving him the Batglare. He gulped.

“You’re not Dick,” she stated, “What have you done with him?!”

“What?!” Percy stuttered, “Nothing, I…”

“Then who are you, and where is he?”

She pushed the Batarang harder, making it a bit difficult for him to breathe.

“I’m his brother!” Percy exclaimed, “I’m his twin!”

Barbara took a few steps back in surprise.

“Dick never told me he had a twin,” she mumbled.

Percy smirked, “It’s supposed to be a secret.”

“Does Bruce know?”

He shook his head.

“Who does know, then?”

“Well, our dad, _obviously_ , possibly my girlfriend, Annabeth, now you, and no one else.”

Barbara blinked, “But, your dad’s _dead_?”

Percy grimaced slightly, “See, that’s the thing. John Grayson wasn’t  _ really _ our biological father.”

Babs stared at him, “Who  _ was _ , then?”

“Poseidon.”

She laughed at him, “I’m sorry, could you repeat that? It sounded like you said ‘Poseidon’.”

“I  _ did _ .”

“But, but Poseidon’s not  _ real _ ! He’s a Greek God, a myth, a legend!”

Percy chuckled, “Well, if he was, I would never have existed.”

Barbara gaped at him, “If your dad’s a God, what does that make you and Dick?”

He grinned, “Demigods.”

“Excuse me, what?”

“Demigods. Half humans, half gods.”

“You’re saying there’s _more_ of you?”

“A _whole_ Summer Camp full of them.”

“And you and Dick swapped places and that’s where he is.”

“How did you guess?”

“I’m trained by the World’s Greatest Detective.”

“Right, fair point.”


End file.
